The goal of this project is to improve the health of women and infants by enabling crucial research in areas such as SIDS, insufficient or excessive maternal weight gain, short interpregnancy intervals, and birth defects. Advances in understanding the causes and prevention of these and other problems require studies that include more than one pregnancy/birth for a given woman. The only viable source of data for such studies of reproductive history is birth records. However, birth records will not currently support such research because they do not contain unique maternal IDs and cannot be grouped by the mother. We will create a maternally linked data set for thirteen years of birth records for the eight southeastern states in Federal Region IV (9 million records), which has the worst perinatal outcomes in the country. The demographic and geographic diversity of this population and the large sample size will allow investigation of a broad range of pressing maternal and infant health issues. A public-use file of the linked records will be marketed to investigators at universities and similar institutions. We will develop advanced quantitative methods for maternally linked data, which will be included as analytic aids in the documentation for the file.